In a sauce pot, over medium heat, melt the butter. Add the onion and cook until soft – 2-3 minutes. Add the garlic. Cook for 2 minutes more.
Add the tomato sauce, paste and san marzano tomatoes. Use a potato masher and smash the san marzano tomatoes to release the juices.
Add the chipotle pepper, sugar, salt and pepper.
Heat over medium heat until the sauce comes to a simmer. Allow to simmer as long as you desire. See notes.
5 minutes before serving, add the cream, taste and add more salt and pepper as desired.